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Objective: The objective of the study was to determine the bidirectional transfer of pravastatin across the dually perfused term human placental lobule and its distribution between the tissue and maternal and fetal circuits., Study Design: The transfer of pravastatin was determined in the maternal-to-fetal (n = 11) and fetal-to-maternal (n = 10) directions. Pravastatin was coperfused with its [(3)H]-isotope and the marker compound antipyrine (20 μg/mL) and its [(14)C]-isotope. The concentration of pravastatin in the perfused tissue and the maternal and fetal circuits was determined using liquid scintillation spectrometry. Inside-out vesicles prepared from placental brush border membranes were utilized to investigate the role of efflux transporters in the transplacental transfer of pravastatin., Results: Pravastatin was transferred from the maternal to the fetal circuit and vice versa. In the maternal-to-fetal direction, the distribution of pravastatin at the end of experiment was as follows: 14 ± 5% of the drug was retained by the tissue, 68 ± 5% remained in the maternal circuit, and 18 ± 4% was transferred to the fetal circuit. The normalized transfer of pravastatin (clearance index) to antipyrine in the fetal-to-maternal direction (0.48 ± 0.07) was higher than its transfer in the maternal-to-fetal direction (0.36 ± 0.07, P < .01). Furthermore, pravastatin inhibited the adenosine triphosphate (ATP)-dependent uptake of the paclitaxel and estrone sulfate., Conclusion: The transfer of pravastatin across the dually perfused placental lobule suggests that fetal exposure to pravastatin is plausible. The higher transfer of pravastatin in the fetal-to-maternal direction than the reverse as well as its inhibition of the ATP-dependent uptake of [(3)H]-paclitaxel and [(3)H]-estrone sulfate strongly suggest the involvement of efflux transporters in decreasing its transfer across the placenta and support pravastatin's favorable pharmacokinetic profile in pregnancy., (Copyright © 2013 Mosby, Inc. All rights reserved.)

Objective: Substrates of placental efflux transporters could compete for a single transporter, which could result in an increase in the transfer of each substrate to the fetal circulation. Our aim was to determine the role of placental transporters in the biodisposition of oral hypoglycemic drugs that could be used as monotherapy or in combination therapy for gestational diabetes., Study Design: Inside-out brush border membrane vesicles from term placentas were used to determine the efflux of glyburide, rosiglitazone, and metformin by P-glycoprotein, breast cancer resistance protein, and multidrug resistance protein., Results: Glyburide was transported by multidrug resistance protein (43 +/- 4%); breast cancer resistance protein (25 +/- 5%); and P-glycoprotein (9 +/- 5%). Rosiglitazone was transported predominantly by P-glycoprotein (71 +/- 26%). Metformin was transported by P-glycoprotein (58 +/- 20%) and breast cancer resistance protein (25 +/- 14%)., Conclusion: Multiple placental transporters contribute to efflux of glyburide, rosiglitazone, and metformin. Administration of drug combinations could lead to their competition for efflux transporters., (Copyright 2010 Mosby, Inc. All rights reserved.)

Objective: Determine transplacental transfer and metabolism of 17-alpha-hydroxyprogesterone caproate and its distribution between the tissue and the maternal and fetal circuits of the dually perfused placental lobule., Study Design: 17-alpha-Hydroxyprogesterone caproate (21 ng/mL) and its dual-labeled isotope, 17-alpha-hydroxy-[(3)H] progesterone [(14)C] caproate were added to the maternal circuit. The concentrations of the drug and its metabolite in trophoblast tissue and both circuits were determined by high performance liquid chromatography and liquid scintillation spectrometry., Results: 17-alpha-Hydroxyprogesterone caproate was transferred from the maternal to fetal circuit. After a 4-hour perfusion period, a metabolite of 17-alpha-hydroxyprogesterone caproate that retained both progesterone and caproate moieties was identified in the tissue and the maternal and fetal circuits. Neither 17-alpha-hydroxyprogesterone caproate nor its metabolite, at the concentrations tested, had adverse effect on determined viability and functional parameters of placental tissue., Conclusion: 17-alpha-Hydroxyprogesterone caproate was metabolized by term placental lobule during its perfusion and both parent compound and its metabolite(s) transferred to the fetal circuit.

Objective: The purpose of this study was to determine the transfer characteristics of metformin across placentas that were obtained from uncomplicated pregnancies and from patients with gestational diabetes mellitus., Study Design: The technique of dual perfusion of placental lobule was used. Metformin, 5 microg/mL and its [14C]-isotope were co-transfused with the marker compound antipyrine, 20 microg/mL and its [3H]-isotope from the maternal to fetal circuit. The drug content in both circulations and placental tissue was determined by liquid scintillation spectrometry., Results: The transfer of metformin across term human placentas that were obtained from uncomplicated pregnancies was rapid and was not different from that in placentas that were obtained from patients with gestational diabetes mellitus. Metformin is distributed between the maternal and fetal circuits, with reliable amounts retained by the tissue., Conclusion: In an ex vivo model system, metformin was transferred readily from the maternal to fetal circuit across placentas that were obtained from uncomplicated pregnancies and pregnancies with gestational diabetes mellitus.